Prior to the present invention, typically for immunological testing there have been employed non-toxic disposable plastic plates of plastic such as polyvinyl or polystyrene, for example, to which attachment to the walls thereof by incubation is possible -- as for example would occur upon addition of a fluid/liquid containing antigens to be counted and/or identified. After the incubation period, a tedious procedure of carefully washing each separately of a plurality of vessels per plate is required to both avoid contamination of one from another and to wash away all non-attached antigens, such procedure being attempted and accomplished by a variety of methods, all of which basically envolve the addition of washing water, then the withdrawal of the washing water. Such procedures are time-consuming and require special care and skill, and the results are less than highly accurate because of the difficulty in effecting clean washing even though several washings may be included within a procedure.